Network-instructed handover from WLAN to another radio access network

ABSTRACT

Systems and methods are disclosed for providing a network-instructed handover of a wireless device from a Wireless Local Area Network (WLAN) to a Radio Access Network (RAN) of another Radio Access Technology (RAT), e.g., a 3 rd  Generation Partnership Project (3GPP) or 3 rd  Generation Partnership Project 2 (3GPP2) RAT. In one embodiment, a WLAN access node determines that a handover of a wireless device from the WLAN to another RAN of a different RAT is to be performed and transmits a handover instruction to the wireless device that instructs the wireless device to perform a handover from the WLAN to a RAN of a different RAT. In this manner, the WLAN access node is able to steer the wireless device from the WLAN to a RAN of a different RAT.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/650,616, filed Jul. 14, 2017, now U.S. Pat. No. 10,321,364, which isa continuation of U.S. patent application Ser. No. 14/246,841, filedApr. 7, 2014, now U.S. Pat. No. 9,756,533, which claims the benefit ofprovisional patent application Ser. No. 61/811,732, filed Apr. 13, 2013,the disclosures of which are hereby incorporated herein by reference intheir entireties.

FIELD OF THE DISCLOSURE

The present disclosure relates to a network-instructed handover of awireless device from a Wireless Local Area Network (WLAN) to a RadioAccess Network (RAN) of another Radio Access Technology (RAT), e.g., a3^(rd) Generation Partnership Project (3GPP) or 3^(rd) GenerationPartnership Project 2 (3GPP2) RAT.

BACKGROUND

The Institute for Electrical and Electronics Engineers (IEEE) hascreated and maintains a set of Media Access Control (MAC) and PHYsicallayer (PHY) specifications for implementing Wireless Local Area Network(WLAN) communication. This set of MAC and PHY layer specifications isknown as the IEEE 802.11 specifications (more specifically known as IEEEStandard for Information technology—Telecommunications and informationexchange between systems Local and metropolitan area networks—Specificrequirements Part 11: Wireless LAN Medium Access Control (MAC) andPhysical Layer (PHY) Specifications). WLANs that operate according tothe IEEE 802.11 specifications are also known as Wi-Fi® networks.Currently, Wi-Fi® networks mainly operate in the 2.4 Gigahertz (GHz) orthe 5 GHz frequency band.

The IEEE 802.11 specifications regulate the MAC layer, the PHY layer,and other aspects of each addressable unit, which is referred to as astation (STA) (e.g., an access point or a wireless device), to securecompatibility and inter-operability between access points and wirelessdevices. Wireless devices may also be referred to herein as wirelessterminals, portable devices, or portable terminals. Wi-Fi® networks aregenerally operated in unlicensed bands. As such, communication over aWi-Fi® network may be subject to interference from any number of bothknown and unknown devices. Wi-Fi® networks are commonly used as wirelessextensions to fixed/wired broadband access, e.g., in domesticenvironments and hotspots such as, for example, airports, trainstations, and restaurants.

Recently, Wi-Fi® networks have been subject to increased interest fromcellular network operators. In particular, there has been an increasedinterest in using Wi-Fi® networks as an extension of or as analternative to cellular Radio Access Networks (RANs) to handle thealways increasing wireless bandwidth demands. Cellular network operatorsthat are currently serving mobile devices with, e.g. any of the 3^(rd)Generation Partnership Project (3GPP) technologies, see Wi-Fi® networksas a wireless technology that can provide improved service in theirregular cellular networks. The 3GPP technologies include Long TermEvolution (LTE), Universal Mobile Telecommunications System(UMTS)/Wideband Code Division Multiple Access (WCDMA), and Global Systemfor Mobile Communications (GSM).

The term “operator-controlled Wi-Fi®” refers to a Wi-Fi® deployment thaton some level is integrated with a cellular network operator's existingnetwork and where the 3GPP RAN and the Wi-Fi® wireless access may evenbe connected to the same core network and provide the same services.There is currently quite intense activity in the area ofoperator-controlled Wi-Fi® in several standardization organizations. In3GPP, connection of Wi-Fi® access points to the 3GPP-specified corenetwork is being pursued. In the Wi-Fi® Alliance (WFA), activitiesrelated to certification of Wi-Fi® products are undertaken, which are tosome extent driven by the need to make Wi-Fi® networks a viable wirelesstechnology for cellular operators to support high bandwidth offerings intheir networks. In this regard, the term “Wi-Fi® offload” is commonlyused to refer to a cellular network operator's ability to offloadtraffic from their cellular networks to Wi-Fi® networks, e.g., in peaktraffic hours and in situations when the cellular network for one reasonor another needs to be offloaded, e.g., to provide requested quality ofservice, maximize bandwidth, or simply for coverage.

For a cellular network operator, offering a mix of both Wi-Fi® andcellular (e.g., 3GPP) Radio Access Technologies (RATs) results in newproblems. In particular, some of these problems arise from the fact thatWi-Fi® networks and cellular networks (e.g., 3GPP networks) arestandardized in isolation from one another. As a result, there is a needfor intelligent mechanisms that enable co-existence of the Wi-Fi® andcellular network technologies. One such area is connection management.Further, wireless devices (e.g., LTE User Equipment devices (UEs))usually support both Wi-Fi® and a number of 3GPP cellular technologies.However, many of these wireless devices are basically behaving as twoseparate devices from a radio access perspective. The 3GPP RAN and themodems and protocols that are operating pursuant to the 3GPPspecifications are basically unaware of the Wi-Fi® protocols and modemsthat are operating pursuant to the IEEE 802.11 specifications.

In light of the discussion above, there is a need for systems andmethods that provide intelligent connection management in acommunication system having a mix of both Wi-Fi® and cellular (e.g.,3GPP) RATs.

SUMMARY

Systems and methods relating to a network-instructed handover of awireless device from a Wireless Local Area Network (WLAN) to a RadioAccess Network (RAN) of another Radio Access Technology (RAT), e.g., a3^(rd) Generation Partnership Project (3GPP) or 3^(rd) GenerationPartnership Project 2 (3GPP2) RAT, are disclosed. In one embodiment, amethod of operation of a WLAN access node is provided. In oneembodiment, the method of operation of the WLAN access node includesdetermining that a handover of a wireless device from the WLAN toanother RAN of a different RAT is to be performed and transmitting ahandover instruction to the wireless device that instructs the wirelessdevice to perform a handover from the WLAN to a RAN of a different RAT.In this manner, the WLAN access node is able to steer the wirelessdevice from the WLAN to a RAN of a different RAT.

In one embodiment, the handover is a selective handover. Morespecifically, in one embodiment, the handover is a handover of at leastone but less than all communications sessions (e.g., Internet Protocol(IP) sessions) of the wireless device from the WLAN to a RAN of adifferent RAT. In another embodiment, the handover is a full handover.More specifically, in one embodiment, the handover is a handover of allcommunications sessions (e.g., IP sessions) of the wireless device fromthe WLAN to a RAN of a different RAT.

In one embodiment, the handover instruction is a general instruction toperform a handover from the WLAN to a RAN of a different RAT. In anotherembodiment, the handover instruction includes information thatidentifies the different RAT for the handover.

In yet another embodiment, the handover instruction includes informationthat identifies a target cell in the RAN of the different RAT. Inaddition, in one embodiment, the handover instruction further includesinformation that identifies the different RAT and the RAN of thedifferent RAT. In another embodiment, the handover instruction furtherincludes assistance information that assists the wireless device whenperforming the handover. In one embodiment, the assistance informationincludes at least some system information of the target cell.

In one embodiment, the different RAT is a 3GPP RAT, and the handoverinstruction includes one or more parameters that enable the wirelessdevice to connect to a RAN of the 3GPP RAT.

In one embodiment, the handover instruction includes a retry timer valuethat defines an amount of time that the wireless device should attemptto access the RAN of the different RAT when performing the handover.

In one embodiment, the WLAN is an Institute for Electrical andElectronics Engineers (IEEE) 802.11 wireless network. Still further, inone embodiment, the different RAT is a cellular network RAT. In oneembodiment, the cellular network RAT is a 3GPP or 3GPP2 RAT. Further, inone embodiment, transmitting the handover instruction to the wirelessdevice includes transmitting, to the wireless device, a management frameselected from a group consisting of: a Deauthentication Management frameincluding a reason code that corresponds to the handover instruction anda Disassociation Management frame including a reason code thatcorresponds to the handover instruction. Still further, in oneembodiment, transmitting the management frame further includestransmitting information regarding the handover instruction in one ormore vendor-specific elements within the management frame. In oneembodiment, the information regarding the handover instruction includesat least one of a group consisting of: a target set of networks for thehandover, a target RAT for the handover, a target cell, assistanceinformation that assists the wireless device when performing thehandover, and a 3GPP handover command. Notably, a 3GPP handover commandmay alternatively be referred to herein as a 3GPP handover commandmessage. In another embodiment, the information regarding the handoverinstruction includes a retry timer value that defines an amount of timethat the wireless device should attempt to access the RAN of the 3GPP or3GPP2 RAT when performing the handover.

In one embodiment, the WLAN is an IEEE 802.11 wireless network, thedifferent RAT is a 3GPP or 3GPP2 cellular network RAT, and transmittingthe handover instruction to the wireless device includes transmitting,to the wireless device, an Association Response Management frameincluding the handover instruction. In another embodiment, the WLAN isan IEEE 802.11 wireless network, the different RAT is a 3GPP or 3GPP2cellular network RAT, and transmitting the handover instruction to thewireless device comprises transmitting, to the wireless device, a BasicService Set (BSS) Transition Management frame with zero neighbor reportelements. In one embodiment, transmitting the BSS Transition Managementframe further includes transmitting information regarding the handoverinstruction in one or more vendor-specific elements within the BSSTransition Management frame. In one embodiment, the informationregarding the handover instruction includes at least one of a groupconsisting of: a target set of networks for the handover, a target RATfor the handover, a target cell, assistance information that assists thewireless device when performing the handover, and a 3GPP handovercommand. In another embodiment, the information regarding the handoverinstruction includes a retry timer value that defines an amount of timethat the wireless device should attempt to access the RAN of the 3GPP or3GPP2 RAT when performing the handover.

In one embodiment, the WLAN is an IEEE 802.11 wireless network, thedifferent RAT is a 3GPP or 3GPP2 cellular network RAT, and transmittingthe handover instruction to the wireless device includes transmitting,to the wireless device, a Wireless Network Management Notification(WNM-Notification) Request frame including the handover instructionwithin one or more optional subelements formatted as one or morevendor-specific elements. In one embodiment, the handover instructionincludes at least one of a group consisting of: information indicativeof the 3GPP or 3GPP2 RAT for the handover, a cell identifier of a targetcell in the RAN of the 3GPP or 3GPP2 RAT to which the wireless device isto be handed over, and one or more attachment parameters that indicatewhich communication sessions of the wireless device are to be handedover.

In one embodiment, the WLAN is an IEEE 802.11 wireless network, thedifferent RAT is a 3GPP or 3GPP2 cellular network RAT, and transmittingthe handover instruction to the wireless device includes transmitting,to the wireless device, a WNM-Notification Request frame including thehandover instruction.

In one embodiment, determining that a handover of the wireless devicefrom the WLAN to another RAN of a different RAT is to be performedincludes deciding to initiate a handover to a 3GPP RAT, sending ahandover preparation request to a RAN in a RAN of the 3GPP RAT, andreceiving a handover preparation response from the RAN comprising a 3GPPhandover command. In this embodiment, transmitting the handoverinstruction includes transmitting the 3GPP handover command to thewireless device. Further, in one embodiment, transmitting the 3GPPhandover command includes transmitting a frame selected from a groupconsisting of: a Deauthorization Management frame including the 3GPPhandover command, a Disassociation Management frame including the 3GPPhandover command, an Association Response Management frame including the3GPP handover command, a BSS Transition Management frame including the3GPP handover command, and a WNM-Notification frame (e.g., aWMN-Notification Request frame) including the 3GPP handover command.

In one embodiment, a WLAN access node includes a processor and memorycontaining instructions executable by the processor whereby the WLANaccess node is operative to determine that a handover of a wirelessdevice from a WLAN to another RAN of a different RAT is to be performed,and transmit a handover instruction to the wireless device thatinstructs the wireless device to perform a handover from the WLAN to aRAN of a different RAT. The memory may include additional instructionsexecutable by the processor whereby the WLAN access node is operativeto, e.g., perform any of the embodiments described above.

In another embodiment, a WLAN access node is adapted to determine that ahandover of a wireless device from the WLAN to another RAN of adifferent RAT is to be performed and transmit a handover instruction tothe wireless device that instructs the wireless device to perform ahandover from the WLAN to a RAN of a different RAT. The WLAN access nodemay be further adapted to perform any of the methods described above.

In another embodiment, a WLAN access node includes means for determiningthat a handover of a wireless device from the WLAN to another RAN of adifferent RAT is to be performed and means for transmitting a handoverinstruction to the wireless device that instructs the wireless device toperform a handover from the WLAN to a RAN of a different RAT.

In yet another embodiment, a WLAN access node includes a WLANcommunication module configured to provide WLAN communication with awireless device, a handover decision module configured to determine thata handover of the wireless device from a WLAN to another RAN of adifferent RAT is to be performed, and a handover instruction moduleconfigured to transmit a handover instruction to the wireless devicethat instructs the wireless device to perform a handover from the WLANto a RAN of a different RAT.

In another embodiment, a computer program is provided that includesinstructions which, when executed on at least one processor, cause theat least one processor to carry out any of the methods of operation of aWLAN access node described above. In one embodiment, a carriercontaining the computer program is provided, wherein the carrier is oneof an electronic signal, an optical signal, a radio signal, or acomputer readable storage medium (e.g., a non-transitory computerreadable medium).

In one embodiment, a method of operation of a wireless device isprovided. The method of operation of the wireless device includescommunicating with a WLAN access node, receiving a handover instructionfrom the WLAN access node to perform a handover from a WLAN to anotherRAN of a different RAT, and performing the handover in response toreceiving the handover instruction.

In one embodiment, the handover instruction is an instruction for aselective handover from the WLAN to another RAN of a different RAT, andperforming the handover comprises performing the selective handover. Inanother embodiment, the handover instruction is an instruction for afull handover from the WLAN to another RAN of a different RAT, andperforming the handover comprises performing the full handover.

In one embodiment, the handover instruction is a general instruction toperform a handover to a RAN of a different RAT, and performing thehandover includes performing the handover to a RAN of a different RAT.In another embodiment, the handover instruction includes informationthat identifies the different RAT for the handover, and performing thehandover includes performing the handover to a RAN of the different RATidentified by the information included in the handover instruction.

In yet another embodiment, the handover instruction includes informationthat identifies a target cell in the RAN of the different RAT, andperforming the handover includes performing the handover to the targetcell. In one embodiment, the handover instruction further includesinformation that identifies the different RAT and the RAN of thedifferent RAT. In another embodiment, the handover instruction furtherincludes assistance information that assists the wireless device whenperforming the handover, and performing the handover to the target cellincludes performing the handover to the target cell based on theassistance information. In one embodiment, the assistance informationincludes at least some system information of the target cell.

In one embodiment, the different RAT is a 3GPP RAT, and the handoverinstruction includes one or more parameters that enable the wirelessdevice to connect to a RAN of the 3GPP RAT.

In one embodiment, the handover instruction includes a retry timer valuethat defines an amount of time that the wireless device should attemptto access the RAN of the different RAT when performing the handover.Further, in one embodiment, performing the handover includes retryingthe handover for the amount of time defined by the retry timer value,and notifying the WLAN access node of a handover failure if the handoveris not successful within the amount of time defined by the retry timer.

In one embodiment, the WLAN is an IEEE 802.11 wireless network. Further,in one embodiment, the different RAT is a cellular network RAT. In oneembodiment, the cellular network RAT is a 3GPP or 3GPP2 RAT. Further, inone embodiment, receiving the handover instruction includes receiving amanagement frame transmitted by the WLAN access node, wherein themanagement frame is selected from a group consisting of: aDeauthentication Management frame including a reason code thatcorresponds to the handover instruction and a Disassociation Managementframe including a reason code that corresponds to the handoverinstruction. In another embodiment, receiving the handover instructionincludes receiving an Association Response Management frame includingthe handover instruction from the WLAN access node. In yet anotherembodiment, receiving the handover instruction includes receiving a BSSTransition Management frame with zero neighbor report elements from theWLAN access node. In yet another embodiment, receiving the handoverinstruction includes receiving, from the WLAN access node, aWNM-Notification frame (e.g., a WNM-Notification Request frame)including the handover instruction within one or more optionalsubelements formatted as one or more vendor-specific elements. In yetanother embodiment, receiving the handover instruction includesreceiving a WNM-Notification frame including the handover instructionfrom the WLAN access node.

In one embodiment, receiving the handover instruction includes receivinga 3GPP handover command within a WLAN frame.

In one embodiment, a wireless device is provided. In one embodiment, thewireless device includes a transceiver, a processor, and memorycontaining instructions executable by the processor whereby the wirelessdevice is operative to communicate with a WLAN access node of a WLAN viathe transceiver, receive, via the transceiver, a handover instructionfrom the WLAN access node to perform a handover from the WLAN to anotherRAN of a different RAT, and perform the handover in response toreceiving the handover instruction.

In another embodiment, the wireless device is adapted to communicatewith a WLAN access node of a WLAN, receive a handover instruction fromthe WLAN access node to perform a handover from the WLAN to another RANof a different RAT, and perform the handover in response to receivingthe handover instruction. The wireless device may be further adapted toperform any of the embodiments of the method of operation of thewireless device described above.

In another embodiment, the wireless device includes means forcommunicating with a WLAN access node of a WLAN, means for receiving ahandover instruction from the WLAN access node to perform a handoverfrom the WLAN to another RAN of a different RAT, and means forperforming the handover in response to receiving the handoverinstruction.

In another embodiment, the wireless device includes a WLAN communicationmodule configured to provide WLAN communication with a WLAN access nodeof a WLAN, a handover instruction reception module configured to receivea handover instruction from the WLAN access node to perform a handoverfrom the WLAN to another RAN of a different RAT, and a handover moduleconfigured to perform the handover in response to the handoverinstruction.

In one embodiment, a computer program is provided. The computer programcomprises instructions which, when executed on at least one processor,cause the at least one processor to carry out the method of operation ofa wireless device according to any of the embodiments described above.In one embodiment, a carrier containing the computer program isprovided, wherein the carrier is one of an electronic signal, an opticalsignal, a radio signal, or a computer readable storage medium (e.g., anon-transitory computer readable medium).

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the embodiments in association withthe accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1 illustrates a communication system including a mix of both acellular network and a Wireless Local Area Network (WLAN) that providesa network-instructed handover of a wireless device from the WLAN to thecellular network according to one embodiment of the present disclosure;

FIG. 2 illustrates the operation of the communication system of FIG. 1to perform a network-instructed handover of the wireless device from theWLAN to the cellular network according to one embodiment of the presentdisclosure;

FIG. 3 illustrates a frame structure of an Institute for Electrical andElectronics Engineers (IEEE) 802.11 Deauthentication Management frame oran IEEE 802.11 Disassociation Management frame that is utilized totransmit a handover instruction from a WLAN access node to the wirelessdevice according to one embodiment of the present disclosure;

FIG. 4 illustrates the operation of the communication system of FIG. 1to perform a network-instructed handover of the wireless device from theWLAN to the cellular network according to another embodiment of thepresent disclosure;

FIG. 5 illustrates a frame structure of an IEEE 802.11 AssociationResponse Management frame that is utilized to transmit a handoverinstruction from a WLAN access node to the wireless device according toanother embodiment of the present disclosure;

FIGS. 6A through 6C illustrate a frame structure of a conventional IEEE802.11 Basic Service Set (BSS) Transition Management frame;

FIGS. 7A and 7B illustrate a frame structure of an IEEE 802.11 BSSTransition Management frame that is utilized to transmit a handoverinstruction from a WLAN access node to the wireless device according toanother embodiment of the present disclosure;

FIG. 8 illustrates a frame structure of an IEEE 802.11 Wireless NetworkManagement Notification (WNM-Notification) Request frame;

FIG. 9 illustrates a frame structure of an IEEE 802.11 WNM-NotificationRequest frame with vendor-specific formatting that is utilized totransmit a handover instruction from a WLAN access node to the wirelessdevice according to another embodiment of the present disclosure;

FIG. 10 illustrates a frame structure of an IEEE 802.11 WNM-NotificationRequest Action frame in which optional subelements are formatted withvendor-specific formatting for transmission of a 3^(rd) GenerationPartnership Program Project (3GPP) handover command according to oneembodiment of the present disclosure;

FIGS. 11A and 11B illustrate a frame structure of an IEEE 802.11WNM-Notification Request frame that is utilized to transmit a handoverinstruction for multi-band steering according to another embodiment ofthe present disclosure;

FIG. 12 is a block diagram of one of the base stations of the cellularnetwork of FIG. 1 according to one embodiment of the present disclosure;

FIG. 13 is a functional block diagram of one of the base stations of thecellular network of FIG. 1 according to one embodiment of the presentdisclosure;

FIG. 14 is a block diagram of the WLAN access node of FIG. 1 accordingto one embodiment of the present disclosure;

FIG. 15 is a functional block diagram of the WLAN access node of FIG. 1according to one embodiment of the present disclosure;

FIG. 16 is a block diagram of one of the wireless devices of FIG. 1according to one embodiment of the present disclosure; and

FIG. 17 is a functional block diagram of one of the wireless devices ofFIG. 1 according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

The embodiments set forth below represent information to enable thoseskilled in the art to practice the embodiments and illustrate the bestmode of practicing the embodiments. Upon reading the followingdescription in light of the accompanying drawing figures, those skilledin the art will understand the concepts of the disclosure and willrecognize applications of these concepts not particularly addressedherein. It should be understood that these concepts and applicationsfall within the scope of the disclosure and the accompanying claims.

Systems and methods relating to a network-instructed handover of awireless device from a Wireless Local Area Network (WLAN) to a RadioAccess Network (RAN) of another Radio Access Technology (RAT), e.g., a3^(rd) Generation Partnership Project (3GPP) or 3^(rd) GenerationPartnership Project 2 (3GPP2) RAT, are disclosed. In this regard, FIG. 1illustrates a communication system 10 that includes a cellular RAN 12and a WLAN 14. The cellular RAN 12 includes base stations 16-1 through16-5 (generally referred to herein collectively as base stations 16 andindividually as base station 16) that operate according to a cellularRAT such as, e.g., a 3GPP or 3GPP2 RAT. Some examples of 3GPP and 3GPP2RATs are Long Term Evolution (LTE), Universal Mobile TelecommunicationsSystem (UMTS)/Wideband Code Division Multiple Access (WCDMA), and GlobalSystem for Mobile Communications (GSM) RATs. While five base stations 16are shown in this example, the cellular RAN 12 may include any number ofbase stations 16.

The WLAN 14 includes a WLAN access node 18 that operates according to aWLAN RAT and provides a connection point for the WLAN 14. The WLANaccess node 18 may alternatively be referred to as an access point, awireless access controller, or the like. In the embodiments describedherein, the WLAN RAT is an Institute for Electrical and ElectronicsEngineers (IEEE) 802.11 WLAN RAT (i.e., the WLAN 14 is an IEEE 802.11 orWi-Fi® network). For example, the WLAN 14 may be a Wi-Fi® hotspot.However, the present disclosure is not limited thereto. Other WLAN RATsmay be used. In one embodiment, the WLAN 14 is an operator controlledWLAN, which at some level is integrated with the cellular network(including the cellular RAN 12) of a cellular network operator. Further,while not illustrated, the WLAN 14 and the cellular RAN 12 may beconnected to the same core network (e.g., an Evolved Packet Core (EPC)network for a LTE RAN).

Together, the cellular RAN 12 and the WLAN 14 provide services to anumber of wireless devices 20-1 through 20-5 (generally referred toherein collectively as wireless devices 20 and individually as wirelessdevice 20). While five wireless devices 20 are shown in this example,there may be any number of wireless devices 20 served by the cellularRAN 12 and the WLAN 14. In this example, the wireless devices 20-1 and20-2 are connected to the WLAN 14, whereas the wireless devices 20-3through 20-5 are connected to the cellular RAN 12. The wireless devices20, which may also be referred to as wireless communication devices, mayrepresent any suitable type of device capable of wireless communicationincluding, but not limited to, conventional User Equipment devices (UEs)and other types of cellular telephones; Machine Type Communication(MTC)/Machine-to-Machine (M2M) devices (e.g., wireless sensors ormeters); Radio Frequency Identifiers (RFIDs); WLAN terminals or Stations(STAs); and wireless-capable laptops, tablets, and other computers.

As discussed below, the WLAN access node 18 initiates anetwork-instructed handover of the wireless device 20-1 from the WLAN 14to the cellular RAN 12. Using conventional technology, the wirelessdevice 20-1 would remain connected to the WLAN 14 until a connectionwith the WLAN 14 is no longer possible. In particular, the wirelessdevice 20-1 would remain connected to the WLAN 14 as long as thewireless device 20-1 is within a coverage area 22 of the WLAN 14. As aresult, the wireless device 20-1 would, at least in some scenarios,remain connected to the WLAN 14 even though a connection to the cellularRAN 12 would be better (e.g., provide lower latency, higher data rates,or the like). According to one embodiment of the present disclosure, theWLAN access node 18 operates to initiate a handover of the wirelessdevice 20-1 from the WLAN 14 to the cellular RAN 12 whenever such ahandover is desirable. As one example, the WLAN access node 18 mayinitiate a handover from the WLAN 14 to the cellular RAN 12 when thewireless device 20-1 is greater than a predefined radio distance fromthe WLAN access node 18 as indicated by dashed line 24 but is stillwithin the coverage area 22 of the WLAN 14. As used herein, radiodistance is any value indicative of a quality or strength of a radiosignal received by the wireless device 20-1 from the WLAN access node 18or received by the WLAN access node 18 from the wireless device 20-1(e.g., a Received Signal Strength Indicator (RSSI)).

As discussed below in detail, in order to initiate the handover of thewireless device 20-1 from the WLAN 14 to the cellular RAN 12, the WLANaccess node 18 sends a handover (HO) instruction to the wireless device20-1. The handover instruction may be for a full handover of allcommunication sessions (e.g., Internet Protocol (IP) sessions) from theWLAN 14 to the cellular RAN 12 or a selective handover of one or morecommunications sessions, but potentially less than all communicationssessions, from the WLAN 14 to the cellular RAN 12. In response to thehandover instruction, the wireless device 20-1 performs the handover byconnecting to the cellular RAN 12. In this particular example, thewireless device 20-1 connects to the base station 16-1 (morespecifically to a cell served by the base station 16-1). From thatpoint, the handed over communication session(s) are with the cellularRAN 12. Note that while the embodiment of FIG. 1 and many of the otherembodiments described below focus on a handover from the WLAN 14 to thecellular RAN 12, the present disclosure is not limited thereto. Thehandover may be from the WLAN 14 to any RAN of a different RAT.

FIG. 2 illustrates the operation of the communication system 10 of FIG.1 to perform a network-instructed handover of the wireless device 20-1from the WLAN 14 to the cellular RAN 12 according to one embodiment ofthe present disclosure. As illustrated, initially, communication isestablished between the wireless device 20-1 and the WLAN 14 via theWLAN access node 18 (step 100). At some point, the WLAN access node 18decides, or determines, that a handover of the wireless device 20-1 fromthe WLAN 14 to a RAN of a different RAT is desired (step 102). In oneembodiment, the handover is a full handover of all communication ortraffic (e.g., all IP sessions). In another embodiment, the handover isa selective handover of particular communication or traffic (e.g., onlyIP sessions of certain types). Further, the decision to perform thehandover may be a general decision to perform a handover from the WLAN14. In other words, the handover decision may be a general decision toperform a handover, where it is left to the wireless device 20-1 todetermine a target for the handover. Alternatively, the handoverdecision may be a specific handover decision. More specifically, aspecific handover decision may be a decision to perform a handover to atarget RAT (e.g., LTE), a decision to perform a handover to a target RANof a target RAT type (e.g., a specific LTE RAN), or a decision toperform a handover to a target cell in a target RAN of a target RAT type(e.g., a specific cell in a specific LTE RAN).

Next, the WLAN access node 18 transmits a handover instruction to thewireless device 20-1 (step 104). As discussed below in detail, in oneembodiment, the WLAN 14 is an IEEE 802.11, or Wi-Fi®, network, and thehandover instruction is transmitted within an IEEE 802.11 frame. TheIEEE 802.11 frame may be, for example, a Deauthentication Managementframe, a Disassociation Management frame, an Association ResponseManagement frame, a Basic Service Set (BSS) Transition ManagementRequest Action frame, or a Wireless Network Management Notification(WNM-Notification) frame (e.g., a WNM-Notification Request frame). Thehandover instruction includes information indicating that a handover isto be performed. More specifically, in one embodiment, the handoverinstruction includes one or more of the following:

-   -   a code (e.g., a special status code or a special reason code)        that indicates that a handover is to be performed,    -   information that indicates whether the handover is a full or a        selective handover,    -   information identifying communications sessions to be handed        over in the case of selective handover (e.g., one or more 3GPP        Non-Access Stratum (NAS) parameters indicating a subset of        ongoing traffic or communications sessions (e.g., Packet Data        Network (PDN) connections identified by Access Point Names        (APNs), IP sessions identified by Traffic Flow Templates (TFTs))        that are to be handed over),    -   information that identifies a target RAT for the handover,    -   information that identifies a target RAN for the handover,    -   information that identifies a target cell for the handover,    -   assistance information that will assist the wireless device 20-1        when performing the handover (e.g., at least some System        Information (SI) of a target cell),    -   a 3GPP handover command, which may be received by the WLAN        access node 18 from, e.g., the base station 16 of a target cell        for the handover, or one or more parameters from a 3GPP handover        command,    -   one or more 3GPP NAS parameters (e.g. attachment type, APN,        etc.), and    -   a retry timer that defines an amount of time that the wireless        device 20-1 should attempt to access a RAN of a different RAT        (which, as discussed above, may or may not be specified by the        handover instruction) when performing the handover before, e.g.,        notifying the WLAN access node 18 of a handover failure or        attempting to reestablish the handed over communication with the        WLAN 14.

In response to the handover instruction, the wireless device 20-1performs the handover to, in this example, a cell served by the basestation 16-1 in the cellular RAN 12 (step 106). The manner in which thewireless device 20-1 performs the handover may vary depending on theparticular implementation. As one example, the wireless device 20-1synchronizes to the cell served by the base station 16-1, obtains thesystem information of the cell (if needed), and initiates a randomaccess procedure to establish a connection to the cell served by thebase station 16-1. Once the random access procedure is finished, thefinal steps of the handover are completed. However, the exact detailsdepend on the RAT of the cellular RAN 12 and the particularimplementation (e.g., whether assistance information is provided in thehandover instruction). Once the handover is complete, the wirelessdevice 20-1 communicates with the base station 16-1 (step 108). Inaddition, if the handover was a selective handover, the wireless device20-1 also communicates with the WLAN access node 18 for anycommunications session(s) or traffic that was not handed over (step110).

As discussed above, in some embodiments, the handover instruction istransmitted from the WLAN access node 18 to the wireless device 20-1within a particular type of IEEE 802.11, or Wi-Fi®, frame. In thisregard, FIG. 3 illustrates a frame format for both an IEEE 802.11Deauthentication Management frame and an IEEE 802.11 DisassociationManagement frame that can be utilized to transmit the handoverinstruction according to one embodiment of the present disclosure. Thesetwo frames have the same frame format. Notably, the frame format of theDeauthentication Management frame and the Disassociation Managementframe are defined in Chapters 8.3.3.12 and 8.3.3.4 of “802.11-2012—IEEEStandard for Information technology—Telecommunications and informationexchange between systems Local and metropolitan area networks—Specificrequirements Part 11: Wireless LAN Medium Access Control (MAC) andPhysical Layer (PHY) Specifications,” which is referred to herein as theIEEE 802.11-2012 specification.

Importantly, the frame body of the Deauthentication/Disassociation frameincludes a reason code and one or more vendor-specific elements. In oneembodiment, the handover instruction includes a special reason codetransmitted in the frame body. In particular, the IEEE 802.11-2012specification defines a number of reason codes in Chapter 8.4.1.7. Inthis embodiment, a new reason code is defined for a handover instructionfrom the WLAN 14. Thus, in this embodiment, the WLAN access node 18transmits the handover instruction by transmitting aDeauthentication/Disassociation Management frame including the new, orspecial, reason code defined to indicate a handover instruction.

In addition, in some embodiments, the handover instruction includesadditional information transmitted in the one or more vendor-specificelements of the Deauthentication/Disassociation Management frame. Thisadditional information may include any information related to thehandover of the wireless device 20-1 from the WLAN 14 to, in the exampleof FIGS. 1 and 2, the cellular RAN 12. In one embodiment, the additionalinformation includes one or more of the following:

-   -   A target set of networks (e.g., Public Land Mobile Networks        (PLMNs) or Network Identifier/System Identifiers (NID/SIDs)) for        the handover. The WLAN 14 may belong to a separate network        compared to the cellular RAN 12. Furthermore, different        equivalent PLMNs may exist in the cellular/3GPP domain.    -   A target 3GPP/3GPP2 RAT for the handover (i.e., the 3GPP/3GPP2        RAT to which the wireless device 20-1 should handover to).    -   A target 3GPP/3GPP2 RAT and a target cell for the handover. This        may indicate both the RAT and the cell that the wireless device        20-1 should handover to. The target cell could be indicated as,        e.g., a GSM Cell Global Identity (CGI) (including Mobile Country        Code (MCC), Mobile Network Code (MNC), Location Area Code (LAC),        and Cell Identity (CI)) or any other RAT specific cell        identifier like, e.g., the 28-bit Universal Terrestrial Radio        Access Network (UTRAN) Cell Identifier (UC-Id) including both        Radio Network Controller Identifier (RNC-ID) and Cell-ID (C-Id).        Notably, the UC-Id is 28 bits and parts of the UC-Id are used        for the RNC-ID (e.g., 12 bits) and the rest for the C-Id (e.g.,        16 bits). Then, the whole UC-Id can identify a cell within a        PLMN, and the C-Id can be used to identify a cell within a Radio        Network Subsystem (RNS).    -   Assistance information for assisting the wireless device 20-1        when performing the handover to a target cell in a target RAT.        For example, the assistance information may include at least        some SI elements that the wireless device 20-1 would need to        first read on the target cell. The wireless device 20-1 may be        able to more quickly access the target cell when such assistance        information is already provided to the wireless device 20-1 from        the WLAN 14.    -   A 3GPP handover command as defined in the 3GPP specification for        a target RAT. For example, if the target RAT is GSM, then the        handover command is defined in 3GPP Technical Specification (TS)        44.018 (e.g., version 12.2.0). The same applies for UTRAN and        Evolved UTRAN (E-UTRAN), where the handover command is defined        in 3GPP TS 25.331 (e.g., version 12.1.0) and 36.331 (e.g.,        version 12.1.0), respectively. In this case, the WLAN 14 is        integrated into the cellular network in such a way that it is        possible to perform handover preparation phase signaling towards        the RAN node controlling/handling the target RAT and the target        cell. The handover command is created by the target RAN node        (e.g., the base station 16-1) and provided to the WLAN access        node 18 for transmission to the wireless device 20-1.    -   One or more 3GPP NAS parameters (e.g. attachment type, APN,        etc.).    -   A retry timer that indicates an amount of time that the wireless        device 20-1 should attempt to access the target RAT/cell in any        of the cases described above. If the wireless device 20-1 is        unable to access the target RAN/cell in the amount of time        indicated by the retry timer, in some embodiments, the wireless        device 20-1 should try to abandon the access attempts to the        target RAT/cell and attempt to inform the WLAN 14 (e.g., the        WLAN access node 18) of a handover failure.

As discussed above, in one embodiment, the handover instructiontransmitted by the WLAN access node 18 to the wireless device 20-1 mayinclude a 3GPP handover command. In this regard, FIG. 4 illustrates theoperation of the communication system 10 of FIG. 1 according to oneembodiment in which the handover instruction includes a 3GPP handovercommand. As illustrated, initially, communication is established betweenthe wireless device 20-1 and the WLAN 14 via the WLAN access node 18(step 200). In this embodiment, at some point, the WLAN access node 18decides, or determines, that a handover of the wireless device 20-1 fromthe WLAN 14 to the cellular RAN 12 is desired (step 202). In oneembodiment, the decision is for a full handover. However, in anotherembodiment, the WLAN access node 18 may decide to initiate a full orselective handover. The WLAN access node 18 then sends a handoverpreparation request to the base station 16-1 serving a target cell forthe handover (step 204). In response, the base station 16-1 sends ahandover preparation response including a 3GPP handover command to theWLAN access node 18 (step 206). Note that while the 3GPP handovercommand is used in this example, one or more parameters that arenormally included in a 3GPP handover command may be used instead of afull 3GPP handover command. The communication between the WLAN accessnode 18 and the base station 16-1 in steps 202 and 204 may be directlybetween the base station 16-1 and the WLAN access node 18 via a wired orwireless connection, e.g., a cellular connection, or indirectly through,e.g., a common core network of the cellular RAN 12 and the WLAN 14.

Next, the WLAN access node 18 transmits a handover instruction includingthe 3GPP handover command to the wireless device 20-1 (step 208). Asdiscussed above, in one embodiment, the 3GPP handover command istransmitted in an IEEE 802.11 Deauthentication/Disassociation Managementframe. However, the handover command may be transmitted in other typesof IEEE 802.11 frames. In this embodiment, the handover instruction mayinclude, e.g., a 3GPP RAT type for the handover, a 3GPP RAT Identifier(ID) for the handover, and one or more attach parameters taking the formof a 3GPP handover command or one or more parameters that are normallyincluded in a 3GPP handover command. Additionally, the handoverinstruction may include one or more 3GPP NAS parameters to be used inthe Attach Request as defined in Section 5.3.2.1 of 3GPP TS 23.401(version 12.4.0). These parameters include, for example, APN, attachtype per APN (initial attach, handover attach, handover attach with IPFlow Mobility (IFOM), etc.), TFT, etc.

In response to the handover instruction including the 3GPP handovercommand, the wireless device 20-1 performs the handover to, in thisexample, a cell served by the base station 16-1 in the cellular RAN 12(step 210). Once the handover is complete, the wireless device 20-1communicates with the base station 16-1 (step 212). In addition, if thehandover was a selective handover, the wireless device 20-1 alsocommunicates with the WLAN access node 18 for any communicationssession(s) or traffic that was not handed over (step 214).

As discussed above, the handover instruction may be transmitted invarious types of IEEE 802.11 frames. In this regard, FIGS. 5, 6A through6C, 7A, 7B, and 8-10 illustrate various IEEE 802.11 frame formats thatcan be utilized to transmit the handover instruction from the WLANaccess node 18 to the wireless device 20-1 according to additionalembodiments of the present disclosure. More specifically, FIG. 5illustrates a frame format of an IEEE 802.11 Association ResponseManagement frame as defined in Chapter 8.3.3.6 of the IEEE 802.11-2012specification. As illustrated, the frame body of the AssociationResponse Management frame includes, among other elements, a status codeelement and one or more vendor-specific elements. In one embodiment, thehandover instruction includes a special status code transmitted in theframe body, where the special status code is a new status code definedfor a handover instruction from the WLAN 14. Thus, in this embodiment,the WLAN access node 18 transmits the handover instruction bytransmitting an Association Response Management frame including the new,or special, status code defined to indicate a handover instruction.

In addition, in some embodiments, the handover instruction includesadditional information transmitted in the one or more vendor-specificelements of the Association Response Management frame. This additionalinformation may include any information related to the handover of thewireless device 20-1 from the WLAN 14 to, in the example of FIGS. 1 and2, the cellular RAN 12. This additional information may include, forexample, any of the information described above with respect to theDeauthentication/Disassociation Management frame.

Still further, in another embodiment, the handover instruction may useonly the one or more vendor-specific elements (i.e., without any specialstatus code). For example, in one particular embodiment, the informationtransmitted in the one or more vendor-specific elements includes a codeindicative of the handover instruction. Additional information relatedto the handover may also be transmitted in the vendor-specificelement(s), as discussed above.

FIGS. 6A through 6C illustrate a frame format of a BSS TransitionManagement Request frame as defined in Chapter 8.5.14.9 of the IEEE802.11-2012 specification. Normally, the BSS Transition ManagementRequest frame includes one or more Neighbor Report elements. Asillustrated in FIGS. 7A and 7B, in one embodiment, the handoverinstruction is transmitted from the WLAN access node 18 to the wirelessdevice 20-1 by transmitting a BSS Transition Management Request frame,and specifically a BSS Transition Management Request frame including aBSS Transition Candidate List Entries field, with zero Neighbor Reportelements. This frame will then be interpreted by the wireless device20-1 as a handover instruction. More specifically, zero Neighbor Reportelements may be interpreted as there being no suitable WLAN access nodesto which to transition and, as such, a handover to a RAN of a differentRAT (e.g., the cellular RAN 12) is needed. Further, in some embodiments,the handover instruction includes additional information related to thehandover in the one or more vendor-specific elements. This additionalinformation may include, e.g., any of the additional informationdescribed above with respect to the Deauthentication/DisassociationManagement frame.

FIG. 8 illustrates a frame format for an IEEE WNM-Notification Requestframe as defined Chapter 8.5.14.28 of the IEEE 802.11-2012specification. Importantly, the WNM-Notification Request frame includesone or more optional subelements in which the handover instruction istransmitted from the WLAN access node 18 to the wireless device 20-1according to one embodiment of the present disclosure. Morespecifically, in one embodiment, the optional subelement(s) of theWNM-Notification Request frame are formatted as vendor-specificelement(s), as illustrated in FIG. 9. While not essential for thepresent disclosure, the optional subelement(s) may be formatted asvendor-specific element(s) as defined in Chapter 8.4.2.28 of the IEEE802.11-2012 specification. The handover instruction can then betransmitted as the vendor-specific content of the optionalsubelement(s). The handover instruction may include, as described above,a code that indicates a handover instruction and/or information relatedto the desired handover (e.g., target RAT, target RAN, target cell, 3GPPhandover command, 3GPP NAS parameters, retry timer, or the like, or anycombination thereof).

In one embodiment, the vendor-specific element of the WNM-NotificationRequest frame is formatted in accordance to the Wi-Fi® Alliance (WFA)rules for such frame types, as illustrated in FIG. 10. In thisembodiment, the fields of the WFA formatted vendor-specific elementincludes the following information:

-   -   A subelement ID set to value “221” (“Vendor Specific,” as        specified by the IEEE 802.11-2012 specification).    -   An Organization Identifier set to “0x 50 6F 9A” (as requested by        the WFA guidelines).    -   A “Type” set to “0x01” (in conjunction with “WFA Technology        Assignments” instructions).    -   The 3GPP RAT Type indicates a handover preference in regard to a        specific RAT to be chosen by the wireless device 20-1 (i.e., a        target RAT). In one embodiment, the 3GPP RAT Type field can        assume the following values:        -   0: Reserved        -   1: Any RAT        -   2: Global System for Mobile Communications Enhanced Data            Rates for Global Evolution Radio Access Network (GERAN)        -   3: UTRAN        -   4: E-UTRAN        -   5-255: Reserved    -   A 3GPP RAT ID specifies an ID of target 3GPP RAN node for the        handover (e.g., an ID of the target base station 16).        Still further, in some embodiments, the handover may be either a        full or a selective handover. In this regard, the WFA formatted        vendor-specific element may optionally include one or more        attachment parameters indicating a subset of ongoing traffic or        communications sessions (e.g., IP sessions) that are to be        handed over. Examples of such attachment parameters include, but        are not limited to, APN(s) to be handed over, attach type per        APN (initial attach, handover attach, handover attach with IFOM,        etc.), TFTs indicating n-tuples to be handed over, or the like,        or any combination thereof. Notably, an APN identifies a PDN        that the wireless device 20-1 communicates with via the WLAN 14        such as, for example, the Internet, an IP Multimedia System        (IMS) network, an enterprise network, or the like. Note that the        information discussed above may be transmitted in other types of        IEEE 802.11 frames (e.g., a Deauthentication Management frame, a        Disassociation Management frame, an Association Request        Management frame, a BSS Transition Management Request Action        frame, or the like). Similarly, the information discussed above        with respect to the WFA formatted WNM-Notification Request frame        of FIG. 10 is only one example of the information included in a        handover instruction. Additional or alternative information may        be included in the handover instruction.

The embodiments described above focus on steering wireless devices 20from the WLAN 14 to the cellular RAN 12 (or at least from the WLAN 14 toa RAN of a different RAT). FIGS. 11A and 11B illustrate a modified IEEE802.11 WNM-Notification Request frame that can be utilized formulti-band steering according to one embodiment of the presentdisclosure. More specifically, the WLAN 14 may include multiple WLANaccess nodes 18 operating in different frequency bands (e.g., the 2.4and 5 Gigahertz (GHz) frequency bands) or a single WLAN access node 18that operates at two or more frequency bands. Multi-band steering issteering wireless devices 20 from one WLAN frequency band to anotherWLAN frequency band. The WNM-Notification Request frame of FIGS. 11A and11B includes BSS Transition Management capabilities. Using the BSSTransition Management capabilities, the WNM-Notification Request framecan be transmitted by the WLAN 18 to, e.g., the wireless device 20-2 tosteer the wireless device 20-2 from one frequency band of the WLAN 14 toanother frequency band of the WLAN 14.

Particular implementations of the embodiments described herein introducea mechanism by which a WLAN access node can steer a wireless device toanother RAT. Some implementations of the embodiments described above arerather simple and can be implemented with a minimum of effort by bothnetwork and wireless device vendors. Also, some implementations of theembodiments described herein utilize elements of standardized solutionsand thus can be implemented without an excessive amount of substantialchanges to, e.g., the IEEE 802.11-2012 specifications.

Some implementations of the embodiments described above introduce afull-fledged solution that can enable a WLAN access node to communicatean all-traffic, or full, handover of all traffic or a selective handoverof only certain type(s) of traffic (i.e., the WLAN access node cancommunicate a handover at a desired level of granularity). Furthermore,some implementations of the embodiments described herein provide theWLAN access node with the ability to specify a target 3GPP RAT for ahandover. Still other embodiments provide enhanced WLAN multibandsteering that can be communicated with the same type of frame as ahandover instruction, requiring less implementation efforts.

While the base stations 16 (or any type of as cellular access nodes) maybe implemented in hardware or any combination of hardware and/orsoftware, FIG. 12 is a block diagram of one of the base stations 16 ofFIG. 1 according to one embodiment of the present disclosure. Note thatwhile the base stations 16 are discussed herein, the functionality ofthe base stations 16 described herein can be performed by any type ofcellular access node (e.g., a RAN node, a base station, an enhanced NodeB (eNodeB), a Radio Network Controller (RNC), or the like). Asillustrated, the base station 16 includes a baseband unit 26 including aprocessor 28, memory 30, and a network interface 32 and a radio unit 34including a transceiver 36 coupled to one or more antennas 38. In oneembodiment, the functionality of the base station 16 described herein isimplemented in software stored in the memory 30 and executed by theprocessor 28. Additionally, the base station 16 may include additionalcomponents responsible for providing additional functionality, includingany of the functionality described above and/or any functionalitynecessary to support the embodiments described herein.

In one embodiment, a computer program is provided that includesinstructions which, when executed on at least one processor, cause theat least one processor to carry out any of the embodiments of the basestation 16 described above. In one embodiment, a carrier containing thecomputer program is provided, wherein the carrier is one of anelectronic signal, an optical signal, a radio signal, or a computerreadable storage medium (e.g., a non-transitory computer readablemedium).

FIG. 13 is a functional block diagram of one of the base stations 16 ofFIG. 1 according to one embodiment of the present disclosure. Asillustrated, the base station 16 includes a handover module 40 and acommunication module 42, both of which are implemented in softwareexecuted by one or more processors (e.g., the processor 28 of FIG. 12).The handover module 40 operates along with, e.g., the wireless device20-1 to perform the handover of the wireless device 20-1 to a cellserved by the base station 16. In addition, in some embodiments, thehandover module 40 handles handover preparation requests received fromthe WLAN access node 18 and builds a 3GPP Handover command message thatis sent directly or indirectly to the WLAN access node 18 as part of ahandover preparation response. The communication module 42 providescommunication with the wireless device 20-1 once the wireless device20-1 is handed over to the cell served by the base station 16.

While the WLAN access node 18 may be implemented in any type of hardwareor any combination of hardware and software, FIG. 14 is a block diagramof the WLAN access node 18 of FIG. 1 according to one embodiment of thepresent disclosure. As illustrated, the WLAN access node 18 includes aprocessor 44, memory 46, and a transceiver 48 coupled to one or moreantennas 50. In particular embodiments, some or all of the functionalitydescribed above as being provided by the WLAN access node 18 may beprovided by the processor 44 executing instructions stored on acomputer-readable medium, such as the memory 46. Alternative embodimentsof the WLAN access node 18 may include additional components responsiblefor providing additional functionality, including any of thefunctionality identified above and/or any functionality necessary tosupport the embodiments described above.

In one embodiment, a computer program is provided that includesinstructions which, when executed on at least one processor, cause theat least one processor to carry out any of the embodiments of the WLANaccess node 18 described above. In one embodiment, a carrier containingthe computer program is provided, wherein the carrier is one of anelectronic signal, an optical signal, a radio signal, or a computerreadable storage medium (e.g., a non-transitory computer readablemedium).

FIG. 15 is a functional block diagram of the WLAN access node 18 of FIG.1 according to one embodiment of the present disclosure. As illustrated,the WLAN access node 18 includes a WLAN communication module 52, ahandover decision module 54, and a handover instruction module 56, eachof which is implemented in software that is executed by one or moreprocessors of the WLAN access node 18 to provide the functionalitydescribed herein. The WLAN communication module 52 providescommunication with wireless devices 20 connected to the WLAN 14. Thehandover decision module 54 decides when a handover of a wireless device20 from the WLAN 14 to another RAT is to be performed. The handoverinstruction module 56 provides handover instructions to wireless devices20 when appropriate. While not illustrated, the WLAN access node 18 mayinclude additional modules such as, for example, a communication modulefor communication to and/or from the cellular RAN 12 (e.g., to and/orfrom the base station 16 in the cellular RAN 12, e.g., directly or via acommon core network).

While the wireless devices 20 may be implemented in any type of hardwareor any combination of hardware and software, FIG. 16 is a block diagramof one of the wireless devices 20 of FIG. 1 according to one embodimentof the present disclosure. As illustrated, the wireless device 20includes a processor 58, memory 60, and a transceiver 62 coupled to oneor more antennas 64. In particular embodiments, some or all of thefunctionality described above as being provided by the wireless device20 may be provided by the processor 58 executing instructions stored ona computer-readable medium, such as the memory 60. Alternativeembodiments of the wireless device 20 may include additional componentsresponsible for providing additional functionality, including any of thefunctionality identified above and/or any functionality necessary tosupport the embodiments described above.

In one embodiment, a computer program is provided that includesinstructions which, when executed on at least one processor, cause theat least one processor to carry out any of the embodiments of thewireless device 20 described above. In one embodiment, a carriercontaining the computer program is provided, wherein the carrier is oneof an electronic signal, an optical signal, a radio signal, or acomputer readable storage medium (e.g., a non-transitory computerreadable medium).

FIG. 17 is a functional block diagram of one of the wireless devices 20of FIG. 1 according to one embodiment of the present disclosure. Asillustrated, the wireless device 20 includes a WLAN communication module66, a handover instruction reception module 68, a handover module 70,and a cellular network communication module 72, each of which isimplemented in software that is executed by one or more processors ofthe wireless device 20 to provide the functionality described herein.The WLAN communication module 66 provides communication with the WLANaccess node 18 of the WLAN 14. The handover instruction reception module68 operates to receive a handover instruction from the WLAN access node18. The handover module 70 operates to perform a handover form the WLAN14 to another RAT, e.g., the 3GPP RAT of the cellular RAN 12, when ahandover instruction is received by the handover instruction receptionmodule 68. The cellular network communication module 72 providescommunication with the cellular RAN 12.

The following acronyms are used throughout this disclosure.

-   -   3GPP 3^(rd) Generation Partnership Project    -   3GPP2 3^(rd) Generation Partnership Project 2    -   APN Access Point Name    -   BSS Basic Service Set    -   CGI Cell Global Identity    -   CI Cell Identity    -   C-Id Cell Identifier    -   eNodeB Evolved Universal Terrestrial Radio Access Network NodeB    -   EPC Evolved Packet Core    -   E-UTRAN Evolved Universal Terrestrial Radio Access Network    -   GERAN Global System for Mobile Communications Enhanced Data        Rates for Global Evolution Radio Access Network    -   GHz Gigahertz    -   GSM Global System for Mobile Communications    -   HO Handover    -   ID Identifier    -   IEEE Institute for Electrical and Electronics Engineers    -   IFOM Internet Protocol Flow Mobility    -   IMS Internet Protocol Multimedia System    -   IP Internet Protocol    -   LAC Location Area Code    -   LTE Long Term Evolution    -   M2M Machine-to-Machine    -   MAC Media Access Control    -   MCC Mobile Country Code    -   MNC Mobile Network Code    -   MTC Machine Type Communication    -   NAS Non-Access Stratum    -   NID Network Identifier    -   PDN Packet Data Network    -   PHY PHYsical Layer    -   PLMN Public Land Mobile Network    -   RAN Radio Access Network    -   RAT Radio Access Technology    -   RFID Radio Frequency Identifier    -   RNC Radio Network Controller    -   RNC-ID Radio Network Controller Identifier    -   RNS Radio Network Subsystem    -   RSSI Received Signal Strength Indicator    -   SI System Information    -   SID System Identifier    -   STA Station    -   TFT Traffic Flow Template    -   TS Technical Specification    -   UC-Id Universal Terrestrial Radio Access Network Cell Identifier    -   UE User Equipment    -   UMTS Universal Mobile Telecommunications System    -   UTRAN Universal Terrestrial Radio Access Network    -   WCDMA Wideband Code Division Multiple Access    -   WFA Wi-Fi® Alliance    -   WLAN Wireless Local Area Network    -   WNM-Notification Wireless Network Management Notification

Those skilled in the art will recognize improvements and modificationsto the embodiments of the present disclosure. All such improvements andmodifications are considered within the scope of the concepts disclosedherein and the claims that follow.

What is claimed is:
 1. A method of operation of a Wireless Local AccessNetwork, WLAN, node, the method comprising: determining that a handoverof a wireless device from a WLAN to another radio access network of adifferent radio access technology is to be performed; and instructingthe wireless device to perform the handover from the WLAN to the radioaccess network of the different radio access technology, whereininstructing the wireless device to perform the handover comprisessending information that indicates whether the handover is a fullhandover of all communication sessions or a selective handover of one ormore but less than all communication sessions, and wherein the WLAN nodecan perform both the full handover and the selective handover.
 2. Themethod of claim 1 wherein instructing the wireless device to perform thehandover comprises sending at least one of: information that identifiesthe different radio access technology for the handover; information thatidentifies a target set of networks for the handover; information thatidentifies the radio access network of the different radio accesstechnology; information that identifies a target cell in the radioaccess network of the different radio access technology; assistanceinformation that assists the wireless device when performing thehandover; a Third Generation Partnership Project, 3GPP, handovercommand; and/or a Non-Access Stratum, NAS, parameter.
 3. The method ofclaim 1 wherein instructing the wireless device to perform the handovercomprises sending a retry timer value that defines an amount of timethat the wireless device should attempt to access the radio accessnetwork of the different radio access technology when performing thehandover.
 4. The method of claim 1 wherein the WLAN is an IEEE 802.11wireless network.
 5. The method of claim 4 wherein the different radioaccess technology is a cellular network radio access technology.
 6. Themethod of claim 5 wherein the cellular network radio access technologyis a Third Generation Partnership Project, 3GPP, or Third GenerationPartnership Project 2, 3GPP2, radio access technology.
 7. The method ofclaim 6 wherein instructing the wireless device to perform the handovercomprises sending, to the wireless device, a management frame selectedfrom a group consisting of: a Basic Service Set, BSS, TransitionManagement, BTM, frame with zero neighbor report elements; a BTM framewith zero neighbor report elements and with information regarding thehandover instruction in one or more vendor-specific elements within theBTM frame; a Deauthentication Management frame comprising a reason codethat corresponds to the handover instruction; a DisassociationManagement frame comprising a reason code that corresponds to thehandover instruction; an Association Response Management framecomprising the handover instruction from the WLAN node; and a WirelessNetwork Management Notification, WNM-Notification, Request framecomprising the handover instruction within one or more optionalsubelements formatted as one or more vendor-specific elements.
 8. Themethod of claim 7 wherein sending the management frame further comprisessending information regarding the handover instruction in one or morevendor-specific elements within the management frame.
 9. The method ofclaim 1 wherein: determining that the handover of the wireless devicefrom the WLAN to the radio access network of the different radio accesstechnology is to be performed comprises: deciding to initiate a handoverto a Third Generation Partnership Project, 3GPP, radio accesstechnology; sending a handover preparation request to a radio accessnode in a radio access network of the 3GPP radio access technology; andreceiving a handover preparation response from the radio access nodecomprising a 3GPP handover command; and instructing the wireless deviceto perform the handover comprises sending the 3GPP handover command tothe wireless device.
 10. A Wireless Local Access Network, WLAN, nodecomprising: a processor; and memory containing instructions executableby the processor whereby the WLAN node is operative to: determine that ahandover of a wireless device from a WLAN to another radio accessnetwork of a different radio access technology is to be performed; andsend information that indicates whether the handover is a full handoverof all communication sessions or a selective handover of one or more butless than all communication sessions to thereby instruct the wirelessdevice to perform the handover from the WLAN to the radio access networkof the different radio access technology, wherein the WLAN node canperform both the full handover and the selective handover.
 11. A methodof operation of a wireless device, comprising: communicating with aWireless Local Access Network, WLAN, node; receiving an instruction fromthe WLAN node to perform a handover from a WLAN to another radio accessnetwork of a different radio access technology, wherein receiving theinstruction to perform the handover comprises receiving information thatindicates whether the handover is a full handover of all communicationsessions or a selective handover of one or more but less than allcommunication sessions, and wherein the WLAN node can perform both fullhandovers and selective handovers; and performing the handover inresponse to receiving the instruction.
 12. The method of claim 11wherein receiving the instruction to perform the handover comprises:receiving at least one of: information that identifies the differentradio access technology for the handover; information that identifies atarget set of networks for the handover; information that identifies theradio access network of the different radio access technology;information that identifies a target cell in the radio access network ofthe different radio access technology; assistance information thatassists the wireless device when performing the handover; a ThirdGeneration Partnership Project, 3GPP, handover command; and/or aNon-Access Stratum, NAS, parameter; and performing the handovercomprises performing the handover to the radio access network of thedifferent radio access technology identified by the information includedin the handover instruction.
 13. The method of claim 11 whereinreceiving the instruction to perform the handover comprises receiving aretry timer value that defines an amount of time that the wirelessdevice should attempt to access the radio access network of thedifferent radio access technology when performing the handover.
 14. Themethod of claim 11 wherein the WLAN is an IEEE 802.11 wireless network.15. The method of claim 14 wherein the different radio access technologyis a cellular network radio access technology.
 16. The method of claim15 wherein the cellular network radio access technology is a ThirdGeneration Partnership Project, 3GPP, or Third Generation PartnershipProject 2, 3GPP2, radio access technology.
 17. The method of claim 16wherein receiving the instruction to perform the handover comprisesreceiving a management frame transmitted by the WLAN node, themanagement frame selected from a group consisting of: a Basic ServiceSet, BSS, Transition Management, BTM, frame with zero neighbor reportelements; a BTM frame with zero neighbor report elements and withinformation regarding the handover instruction in one or morevendor-specific elements within the BTM frame; a DeauthenticationManagement frame comprising a reason code that corresponds to thehandover instruction; a Disassociation Management frame comprising areason code that corresponds to the handover instruction; an AssociationResponse Management frame comprising the handover instruction from theWLAN node; and a Wireless Network Management Notification,WNM-Notification, Request frame comprising the handover instructionwithin one or more optional subelements formatted as one or morevendor-specific elements.